The present invention relates to knee prosthetics of the type, including a tibia part, which will be fixed to a tibia that has been prepared. It includes a tibia plate, which will co-operate with at least one meniscal element by a first side, and co-operate with a resection plan of the tibia by a second side. It includes a tibia pin as part of the tibia plate, which will penetrate inside the tibia so that the tibia part can be fixed onto it. It includes at least one tibia block for thickening, which will fit flatly between the second side of the tibia plate and the tibia itself, in order to compensate for a lack of local bone tissue between the tibia and the resection plan. The tibia block co-operates with the tibia plate by way of complementary fixating means, featured on the tibia block and the tibia plate.
Such a compensating tibia block is used when a lack or absence of bone tissue exists underneath the tibia resection plan, and a new resection cannot be carried out, as can sometimes be the case with modifying a single-compartment knee prosthetic or poor bone quality, ie in the case of arthritis.
The aim of the invention is to provide a simple and reliable assembly of the tibia block onto the tibia part of the prosthetic.
To this end, the prosthetic according to the invention is characterised by the complementary fixating means being of the pin and retaining-hole which are held by the tibia block and the base of the tibia pin.
According to the present invention, in the assembly mode the pin is inserted into a hole to ensure the assembly and retaining of the tibia block on the base of the tibia pin.
According to a second aspect of the preferred invention, the pin is featured on the base of the tibia pin and the hole is implemented in the tibia block; this pin may constitute the base of an anchoring ridge in the tibia, connected with the tibia pin.
The pin advantageously features a shrunk shaft, distant from its free extremity, which will receive at least one locking bulge implemented at the opening of the retaining hole.
The complementary fixating means preferably include at least one ridge to allow for the deformation of the material in order to achieve an elastic clamping of the pin and the hole and/or the penetration of the pin in the hole. This ridge can extend either along the hole on at least part of its length and a small distance away from it in order to define a flexing plate with it, or along the pin on at least part of its length and up to its free extremity so as to define two flexing tongues.
The pin and the hole can have a general direction which follows the axis of the tibia pin.
In order to assemble the tibia block on either side of the tibia pin, the tibia pin includes part of said fixating means, for instance two pins which are symmetrical with regard to the median antero-posterior plane of the tibia pin.
The complementary fixating means are, for instance, placed so that the tibia block assembles on the base of the tibia pin by a sliding movement perpendicular to the sides of the tibia plate and parallel to the axis of the tibia pin. A variation involves the complementary fixating means placed so that the tibia block assembles on the base of the tibia pin by a sliding movement, parallel to the sides of the tibia plate and perpendicular to the axis of the tibia pin.